When do you think the next main Halo game will be released?

Personally, I'm thinking a reveal at 2017 E3 with a launch in late 2018. Unless it's a Scorpio launch title...
I suspect it will be a Scorpio launch title. That will make it a solid 2 years since Halo 5. They have their new engine, so they have a better starting point than five did. I'm getting to the point were I'm starting to want the next one!
 
At the end of halo 5 it sounded like they were deep into the sequel. I'm betting it revolves around the elite's homeworld.